Currently, a 40 gigabit (G) Quad Small Form-factor Pluggable Plus (QSFP+), 100 G Centum (C) Form-Factor Pluggable 2 (CFP2), and CFP4 optical modules all require a Photonic Integrated Device Transmitter Optical Subassembly (PID TOSA) that collects 4 beams of light emitted by a laser from 4 ports and outputs the light through 1 port. This type of component requires a small size and high density, especially for a 100 G CFP2/CFP4 or a 400 G module. Because a light source needs to meet the local area network (LAN) Emulation Wavelength Division Multiplexing (LANE WDM) or even the Dense Wavelength Division Multiplexing (DWDM) standard, a wavelength interval is small and light combination is especially difficult.
Currently, there are mainly two implementation manners of PID TOSA, which are respectively as follows.
(1) ZigZag Filter optical multiplexor (OMUX) (an optical multiplexer formed by a zigzag optical path filter) light combination solution: as shown in FIG. 1, multiple WDM thin-film filters are connected in series, and different effects of reflection and transmission by the WDM filters on light in different paths are used to eventually combine 4 beams of light on a public port for output. Disadvantages of this solution are as follows. Multiple Thin-Film Filters (TFFs) are required, optical distances of different paths are not balanced, and power of light emitted differs significantly; it is very difficult to insert another optical element into the OMUX, and length of the component is large; costs of multiple WDM TFFs are high; an assembly process is complex, and it is difficult to fabricate the OMUX; and this solution is not suitable for DWDM.
(2) Arrayed Waveguide Grating (AWG) light combination solution: as shown in FIG. 2, in the AWG light combination solution, an arrayed waveguide grating chip is used to combine light output by multiple light sources into one beam for output. Disadvantages of this solution are as follows. Packaging loss is relatively large because of use of the AWG; meanwhile, it is relatively difficult to fabricate the AWG; and the AWG generally works at a constant temperature, which requires temperature control.
It can be learned that current optical multiplexers all have such disadvantages as a large package size, large packaging loss, or a complex manufacturing process.